Antenatal care in pregnancies at risk of alloimmune thrombocytopenia: Report of 19 cases in 16 families

Objective: To assess accuracy of a management program in patients at risk for alloimmune thrombocytopenia (NAITP) and to describe perinatal outcomes. Study design: Nineteen fetuses at risk of thrombocytopenia were identified using obstetric history, HLA type of the mother and fetal phenotyping in cases where paternal heterozygozity for the offending antigen was present. Cordocentesis was timed according to obstetric history and performed with safety precautions to prevent haemorrhage, High dose intravenous gamma globulin (IVIG) was administered to the mother in cases with a fetal platelet count < 100 x 10(9)/l. Results: The platelet antagonisms were distributed as follows: HPA-1a in 15 patients, HPA-5a in two, HPA-3a in one, with one further woman who had antibodies against a private antigen. All multigravidas (N = 18) had previously given birth to an infant with NAITP and two of those infants had experienced severe bleeding. Two fetuses were negative for the offending antigen. The median and mean platelet count at first cordocentesis was 26 and 75 x 10(9)/l respectively (range 3-276). A total of 46 cordocenteses were carried out, of which 37 were followed by platelet transfusions. Bleeding complications were not observed. IVIG was administered to eight mothers and two fetuses responded. Nine infants were delivered by caesarean section (CS) and 10 vaginally at a mean gestational age of 37 weeks (range 34-41). The median and mean platelet count at birth was 141.5 and 140 x 10(9)/l, respectively (range 36-314). Ultrasound examination, both ante- and postnatally, revealed no intracranial haemorrhages. There was one procedure related neonatal death and one infant suffered from convulsions in the neonatal period due to a sinus thrombosis, possibly related to the platelet transfusions. Conclusions: When obstetric history is taken into account cordocentesis in NAITP can be postponed. Safety recommendations described in this study allow cordocentesis without bleeding complications. However, our study does not support routine cordocentesis in patients with a history of NAITP. Both the risks of cordocentesis, and the lack of prospective data on the magnitude of the risk of intrauterine or peripartal bleeding, should be considered.